当调用多个静态方法时，使用 Mockito 验证静态方法调用

Question

I am trying to verify that a static method is called during the test. However, it throws an exception due to the fact that more than one static method of the same class is called during the run. Both these static methods are mocked. The exact exception is like this :-

An unexpected error occurred while verifying a static stub.

To correctly verify a stub, invoke a single static method of com.booking.capacityservicejobs.models.YourStaticClass in the provided lambda.

For example, if a method 'sample' was defined, provide a lambda or anonymous class containing the code.

The code is something like this:-

try (MockedStatic<MyClass1> theMock = Mockito.mockStatic(MyClass1.class);
    MockedStatic<MyClass2> configMock = Mockito.mockStatic(MyClass2.class);
    MockedStatic<MyClass3> downtimeMock = Mockito.mockStatic(MyClass3.class)) {
        theMock.when(MyClass1::lockAndFetch).thenReturn(duRuns);
        theMock.when(() -> MyClass1.startAndUnlock(1)).thenAnswer(invocation -> null);
        configMock.when(() -> MyClass2.getById(1)).thenReturn(dummyConfig);
        downtimeMock.when(() -> MyClass3.isScheduledForRole("app-dummy")).thenReturn(false);
        new RunExecutor().run(); //this executes the code to be tested

        theMock.verify(() -> MyClass1.startAndUnlock(1));
    }

Can I get around this limitation without using powermock? What is the correct way to verify multiple(different) static method calls?

Answer 1

Even if I agree is not a good practice, I have had to deal myself with this issue because I had a dependency with a static utilities class in a library that I could not refactor it, so here goes my answer.

My case it's not exactly as yours: I was testing a method HttpUtils.logProtocolMessages that inside made a call to 2 different static methods in LoggingApi utility class; both mehods returned void. This worked for me:

@Test
public void logProtocolMessageWithoutRequestTest() {

    try (MockedStatic<LoggingApi> mockLog = Mockito.mockLog(LoggingApi.class)){
        mockLog.when(() -> {
            LoggingApi.setProtocolSendMessage(anyString(), anyString());
            LoggingApi.setProtocolReceiveMessage(anyString(), anyString(), anyString());
        }).thenAnswer(Answers.RETURNS_DEFAULTS);
        
        HttpUtils.logProtocolMessages(mockTarget, HttpClientVersion.HTTP_2, response, null);
        
        mockLog .verify(() -> JcatLoggingApi.setProtocolSendMessage(anyString(), anyString()));
        mockLog .verify(() -> LoggingApi.setProtocolReceiveMessage(anyString(), anyString(), anyString()));
    }
}

As you can see, the 2 static methods are mocked in the same lambda, both of them instructed to return nothing. I would say that any case going beyond this should consider a redesign (if possible), or even the test itself.

This WILL ONLY work for basic verifications with verify, such as the # of times the mocked methods are invoked. If you try to do more complex checks such as capturing arguments, the limitation of invoking a single static method in the lambda will prevail, and any assertion based on captors will fail because Mockito has not been able to properly inject their values when more than one method in the same mocked static class is invoked.

This is the mockito dependency I used:

<dependency>
    <groupId>org.mockito</groupId>
    <artifactId>mockito-inline</artifactId>
    <version>4.1.0</version>
    <scope>test</scope>
</dependency>